System Design

Demystifying Agentic Search Engines

Agentic search engines—such as Google AI Mode, Perplexity, Bing Copilot, ChatGPT Search no longer means “type keywords, get ten blue links.” AI Search experience capable of understanding tasks, planning queries, calling tools, and synthesizing results and deliver a conversational response with inline citations, minimizing user effort. In this post, I’ll walk through the stack from bottom to top, how it crawls and indexes pages, how it retrieves and ranks information, and how recent features like RAG and Agentic search build upon these foundations.

Design a Modern Recommendation System

Building Modern Recommendation Systems introduces a comprehensive, end-to-end pipeline that drives intelligent recommendations. The post walks through the full machine learning workflow — from raw data preparation and feature engineering to model training, deployment, real-time inference, and system monitoring.

Modeling for Modern Recommendation Systems

This post explores the full RecSys architecture, emphasizing the core models that drive each stage of the RecSys pipeline — from Retrieval for large-scale candidate generation, to Pre-ranking for efficient filtering, Ranking for fine-grained relevance modeling, and Re-ranking for balancing diversity and control.

The ML Factory: Building Production ML Systems